The goal of this proposal is to develop specific, rapid and reversible small-molecule kinase activators to probe specific nodes in kinase signaling. The studies proposed here lay the foundation for the development of a new technique for local activation and characterization of complex cell signaling cascades. Currently, we do not a have systematic mean to rapidly activate and detect responses mediated by individual protein kinases. The development of small-molecule dependent split-kinases could elucidate the dynamic nature of signaling pathways, independent of extrinsic signals, providing a roadmap of specific activation pathways that are dependent on levels of kinase activity. In theory, this strategy could be rapidly implemented for dissecting and probing essentially any protein kinase, based on the high degree of homology within kinase families. Inducible split-kinase constructs will provide a powerful method to study individual protein kinases without the need to design specific inhibitors to each kinase of interest. The studies proposed here will provide a tractable method for increasing the threshold of kinase activity in a selective, rapid and tunable manner to address questions relating kinase function with activation levels. PUBLIC HEALTH RELEVANCE: These global phosphorylation studies will reveal the dynamic nature of signaling pathways and follow how these signals change over time as a function of kinase activity. Small-molecule activation of split-kinases will enable the pharmacological value of a kinase to be examined by circumventing extracellular activation of signaling pathways and potentially discovering new physiologically relevant targets for treating diseases.